Ground-Pound Switch
A Ground Pound Switch is a type of switch that appeared in Super Mario Galaxy. To use this item, Mario must Ground Pound it (hence the name). Upon pressing this switch, a variety of things can happen, mainly making Star Bits or coins appear.
It is interesting to note that there are also timed ground pound switches, tree stumps which have similar effects, and grey ground-pound switches that make walls fall down, making other areas accessible.
They are also shown again in Super Mario Galaxy 2, having the same functions like in the first game. However, there are also Ground Pound Switches that cause slow motion for everything except for Mario. They appeared in Space Storm Galaxy and Clockwork Ruins Galaxy, and were needed to avoid stage hazards.